#include <bits/stdc++.h>

using namespace std;
using ll = long long;

template<typename T> using pq = priority_queue<T, vector<T>, greater<T>>;

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    int H, W, ans=0, x, y, cnt=0, a, xx, yy;
    cin >> H >> W;
    vector used(H, vector<int>(W, -1));
    pq<tuple<int, int, int>> que0, que1;
    vector A(H, vector<int>(W));
    for (int i=0; i<H; i++){
        for (int j=0; j<W; j++) cin >> A[i][j];
    }
    used[0][0] = 1;
    used[H-1][W-1] = 0;

    auto check=[&](int i, int j)->bool{
        return 0 <= i & i < H & 0 <= j & j < W;
    };

    for (int i=0; i<4; i++){
        x = dx[i];
        y = dy[i];
        if (check(x, y)){
            que1.push({A[x][y], x, y});
        }
    }
    for (int i=0; i<4; i++){
        x = dx[i]+H-1;
        y = dy[i]+W-1;
        if (check(x, y)){
            que0.push({A[x][y], x, y});
        }
    }

    while(1){
        cnt++;
        cnt %= 2;
        if (cnt == 1){
            while(!que1.empty()){
                tie(a, x, y) = que1.top();
                que1.pop();
                if (used[x][y] == -1){
                    used[x][y] = 1;
                    ans++;
                    for (int j=0; j<4; j++){
                        xx = x+dx[j];
                        yy = y+dy[j];
                        if (check(xx, yy)){
                            if (used[xx][yy] == 0){
                                cout << ans << endl;
                                return 0;
                            }
                            else if (used[xx][yy] == -1){
                                que1.push({A[xx][yy], xx, yy});
                            }
                        }
                    }
                    break;
                }
            }
        }
        else{
            while(!que0.empty()){
                tie(a, x, y) = que0.top();
                que0.pop();
                if (used[x][y] == -1){
                    used[x][y] = 0;
                    ans++;
                    for (int j=0; j<4; j++){
                        xx = x+dx[j];
                        yy = y+dy[j];
                        if (check(xx, yy)){
                            if (used[xx][yy] == 1){
                                cout << ans << endl;
                                return 0;
                            }
                            else if (used[xx][yy] == -1){
                                que0.push({A[xx][yy], xx, yy});
                            }
                        }
                    }
                    break;
                }
            }
        }
    }

    cout << ans << endl;

    return 0;
}